Java proxy connection user pass

public class Prueba{
	public static void main(String[] args) {
		try {
			String ipProxy = "";
			String portProxy = "";
			String userProxy = "";
			String passProxy = "";
			System.setProperty("http.proxyHost", ipProxy);
			System.setProperty("http.proxyPort", portProxy);
			URL url = new URL("http://www.google.es");
			URLConnection uc = url.openConnection ();
			String encoded = new String (Base64.encode(new String(userProxy + ":" + passProxy ).getBytes()));
			uc.setRequestProperty("Proxy-Authorization", "Basic " + encoded);
			uc.connect();
			InputStream is = uc.getInputStream();
			
			System.out.println(getStringFromInputStream(is));
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	public String getStringFromInputStream(InputStream is){
	      // TODO
	      return null;
	}
}

   public final static Boolean USE_PROXY = false;
   public final static Boolean IS_PROXY_AUTH = false;
   public final static String PROXY_USER = "";
   public final static String PROXY_PASSWORD = "";
   public final static String PROXY_SERVER ="";
   public final static Integer PROXY_PORT = null;
   
   private void configureConnection() {
       if(USE_PROXY) {
           System.setProperty("http.proxyHost", PROXY_SERVER);
           System.setProperty("http.proxyPort", Integer.toString(PROXY_PORT));
           if (IS_PROXY_AUTH) {
               Authenticator.setDefault(new Authenticator() {
                   @Override
                   protected PasswordAuthentication getPasswordAuthentication() {
                       return new PasswordAuthentication(PROXY_USER, PROXY_PASSWORD.toCharArray());
                   }
               });
           } else {
               Authenticator.setDefault(null);
           }
       }
   }